SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '966d75d3428eff6d2d07f4fd20cbd54dd6582a6cae265f582341ddd8331e6049' 
  AND token = 'PU9WWOzQsPXwEnrZxJS19usYGiLgulcrcDWLytZDVS4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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