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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ffd3cd9038f7dbdee0828cb021b1bbeec9a41521d81d16b23c51997edd421d42' 
  AND token = 'i+RCU/jVsTDKEP2+/udSPhIWBLcLklRcB6cJk3dSf5M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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