SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7668dabcf9687420d3974881e53ad72d5ac87442b6c1ae5de5d2c5144e68f852' 
  AND token = 'Z0siAmoaC+ti+rFUY0Uvwbl9pgc9qENIBDyQDfusIJQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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