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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '428d1a0db2173d3916a0af6554df747333374d7022d5bc97bb3c9cb6bc3d4ec9' 
  AND token = 'v9GG+cQNA/jQBPdmn4tb6EQEJFVLV5f/4DzWktvf4DA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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