SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f4249b078f6e370820fe4947af60d68884c2f53587585025f2a91f9a95f6bb5' 
  AND token = 'GE76gjKNszfatWZDdfgzOLwlYhwkwRygHzdMUE5VC8I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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