SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b151f9040b75a7e8cd63fa5664a9963ed91a9fc3374661aa1dc1cc942473747a' 
  AND token = 'ZMzdCRj/OBtUPq+3Pdv9xFgVC1NNa1dKcBuNGOwcFiM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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