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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b728f346ca3f24c0694e366731418e33fb1e6aa9299e75dfdc51a0ed0c970139' 
  AND token = 'AJ+bk0+cA7QUyeRUF706shFcfvJq6g3HxLb0R9YqudQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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