SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe3f4a0dd881a9239cb83037ab28a67f321fcdf1eb889dd545bd8f05a713e51b' 
  AND token = 'nBjLPUlF5qkPFrZkowRB/XvbYAZGImRgQA7uLJ/RUYE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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