SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1bbf8baa78494b9b54051d5ff2d40fdf621a1b2cbf93aab78429b31907998d6a' 
  AND token = 'T+XIv2J+hNSicLbRvkijLMUpc/jNMV2h3GMHOkYwUmU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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