SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6431d736857f80da12e76ef71e0757bb410a09ff877abf9dce0346d5adcead95' 
  AND token = 'huU/GPghjF6dCgnTHWc56KvJyjd9AIcgcAQmws6+ClM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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