SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75ffc294840add4f7fbdb8b822f5a38f72f65fe3133f0ec988d5825d4ccbfdf1' 
  AND token = 'Ft9ZjJPAsCS8nGb0V6VLjBHIYMoosbAoVCJPqCxgflQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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