SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '229ede185e14c1818ab7194fc1a06fc38b3504985ec915055890f8391b18c335' 
  AND token = 'L6/jjOccmzmsVFZVQ9JbH0GqlRkhwmZujE5xGQvgvdc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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