SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '62fccbffc193cbe05f22da229912c9726c39e6d471da300ff6cf8257d9072502' 
  AND token = 'S7rCGPseUSJorM+Cc0BnY5aIUCE/GBAifQtJBSCEAdM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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