SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd592387bb4a9649a5ac6495a47fe73798f39401b0efbee7fffd3072642baa634' 
  AND token = 'DPoerLQ3N+ehbIvvTIcRWrutXsfHe6hDtR1Y0bw1ULc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}