SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75be39e39b64788ef5cf9668f0e014c0414a62293377ecfae4b9441932e23c81' 
  AND token = '7imD7WbJDuzuRWYrQvB9T2VvwkBZNGSduun0CJULZp8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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