SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c847796969ab1d9eeace84806d3701b093f66dad04cc6ce8430c42c5618749fe' 
  AND token = '955i/AlJgogLkrNaEVipylJI5i8eilyvUpjxJ9GuBZ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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