SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51940e483ad9d67f56229fa98b085b5bf85a8ac806a7c58cb6a2b08110a24970' 
  AND token = '/F3jXDB7QBDF5ZAukXFHFr2sPa703VLOaJcpkd2QM10=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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