SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '89c639de2314201a4e5d759364f31db406345385547fe8c31239e147897a6d4f' 
  AND token = 'kMGSuCTEQ+aCa2ulZl5jPV4acMoLOctKRDouuESHEW4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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