SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9e4cc875792b1256c35bbc0785ba8b1bdb35264596f22c42a3db2f576307a511' 
  AND token = 'fXTon+Ja174m8vTX98oIIAS/cMSwFVYZsLCVK9XN2aM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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