SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd536707f03a74676c15834ca73ef9bf50fbc083ebee1f2b737783a45697ac77b' 
  AND token = 'NRSAf21iPhgWpH4/nQpjQGG/mv9wIsqeZ2cJopITzY8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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