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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21579f94093cc49aa0749ebb12a5ace02c217611fab5f05e50bd83b4cff75310' 
  AND token = '4moP76ajTiaoT0c+CmH5JaO+it/miRLfaTsHgwY0dQ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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