SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37ee785a4ee401759d2d9068a4d60a61046dc168d2601e190f3369d4bec90e4f' 
  AND token = 'OFpaL3fNRrdCkzmFlW5PSfa3dzAoNwWLDihPBsVOWls=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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