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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec9fa7ce5ce25086d7d8ee7d45f79b57af30b1943fddfd3684b4d77bfb5d1b21' 
  AND token = '1T9t99tfMKoiL5qe50qcdG1Dodsk94UThtBtByPs8xg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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