SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '551937e5096ac939edc59b6a47ed31f2a87321e72dfcaf0d3664a572cdbee0e9' 
  AND token = 'Me2SannIRUhJKQMdxCr8uAXitn6MRiLPFcDr26JUEeE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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