SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3c7e43b00ff5d757f622598d5fcad7a0d24c75de49c80bfe94249d88a40985e' 
  AND token = 'lxqO9+gDO3TmnxIvfJtcyzw9m1u9ZgmOVbxhZizuEuE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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