SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3b98caf2b50ec8ac64b1aa47982a59cf716b94123b3243b310b5edd541ea64e' 
  AND token = 'wvF2KOc4w1GTjZ6UPHRBr+WeOxh1nsOPGgRhhgeY5Q0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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