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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb0c91dfa5930879e1a9b5cd2f908f1d3a7f215600b0263dfaec68cbc217aa73' 
  AND token = 'MHBxxJlSBQDqqbeE5NkjMPG27LPdW6X24ywJ8RSN/TA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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