SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c0042e4cc1884ccff79b13633f0cd54c504af0598ca98296fce5b97402d68faa' 
  AND token = 'HzJquuHRbzRHDTZI19Q7qGUfrLtJ03SmY97pbc734eo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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