SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'a6dd4ea4b5a3f0ae26d4a83451e11364354f4b2895dacbe827da8fd15d8c5382' 
  AND token = 'LRf1PEV3xweOW4PbPIE/0dc1z6GEZ8/wGKksxCZUZf0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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