SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8eec893486fe219a239ada87b684d57dc36dcba933d28e9ed023ec2770b9706' 
  AND token = 'fWyI6t+BrMKkxZPsz5+UA2Q5sKwxipn6qlJJKOV5G/A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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