SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2c23fe474c8d301a1a68316a7f09c85250c0b97eba8e6da5c781d4fdd8c30260' 
  AND token = 'l94jkkHpPceB2o7FfLW7hK1Go31N1E14biasRz/IeJM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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