SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55f4e8d8fee88a95754c866a7ab5df114696a23789e2d216d959f4b2002f67da' 
  AND token = 'lwvav/XnshBj5DuO7+DU+2fOkoHYjr2fQfJRyg5DfZQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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