SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90dad12f45a1bc1f0421b63d8eea600d1366a7489adb4cbb9fce617911be09e4' 
  AND token = 'XK38EOfFPC2Pm7LOjFLT1whoUhzgm7ICPwwgRYCbDKc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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