SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31c5f9b6f239d9aaa4ba95061736fe799c1287ab349abc5663c16539c3fbc36b' 
  AND token = 'EWPm4vfSkpbZAkZ2KWWN8UJnKYII+RYRJWh5g8ipW2Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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