SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8a14246c178546d6299abb611d45569936edba8330419a45e61fda067186025' 
  AND token = '4+d0pSpwyTpSRttST5OoZdNtuTrRtDjvQOPvgTk4DWo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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