SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f38dfc56bc23c77b340027ac044f03d0f26789e61ca017318e9c16b3d6c1a067' 
  AND token = 'UmklFqbTRBBN6iCTqwPY7ixap6P8CMphAhZcyXP4fiE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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