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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7795e68d44096942a04e641127d1ddd783f08ac5dfe0439b06e3ba33031da56' 
  AND token = 'cHRTLTC7bIRDv31927wXTmchxdb7E7UQavS/naSxE68=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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