SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a906fd734de8598004204658dbd95e9e54d94e6e74d2dd5765965dc2505ad4f8' 
  AND token = 'GqR1g1yStv+ZzNo+vzNwCHcI7U1r6qlHiP4CPsfflDM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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