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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bf23a2a50a5b1bfc53bb2ac21ae2473cb77122b51b41cc2a097559afc1264cae' 
  AND token = 'Xa0OhcjyJ/Sd1/6r8D2SLF1uA8mJgA7DktCEx9/CC3I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}