SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c89f115c96ac0ccfdcfd7119d53ff438320068752bf69da203af968fd239cb4' 
  AND token = 'acn3Guqv0p+GBlLjLymtg9MFEchBkTFgwiKoW5w0gfI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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