SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a31baf528616c5d66044c85ac0050722a1c5db8cd928eb59d20f2081656ec694' 
  AND token = 'OyxVWYfyGldFJA5Gmw/9cTWsYgdwCSGQD/cEMrEAvng=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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