SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a94a53b2ff4078b4f6ef9dc04cd91e60fddd6e1b56547a8a1f574c13c9466ebb' 
  AND token = '8xClvGhzgQr2d7i3cCy0G3BZcjnPqovP9LY4bnz/zpU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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