SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4348fe8708d40b75751f0e772e143628cbc4f8911f3968678d191a92d203d105' 
  AND token = '4LgDCmnC6lMH+4fUv/qXEAXxpPJbZ3bMqK5S+8yoxHo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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