SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6d0efc10ea3661e0b6c972cad7b0e4eb2edf52009787f626dd634caade39f17' 
  AND token = 'w2l+muNe1Igt36BzgXV91nycRJJUphn2fHc5cXaMsLU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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