SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '375e115638200db47d73e8a6ea3d22841ca9100e8b526f38aa4c86ed77a87e58' 
  AND token = '6lB2iOavrqEHLUwqXKvFOLSFcUeM8uhh80/Hrvu7zOQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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