SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cfedbbbfec414c13b9a3f774f9ee3e2da15d079150270ef5d9908c78356d3455' 
  AND token = 'DCMePjCT67o5WUUNea34Q4ieY1ctH2SvCGtRbByCBwE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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