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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '172baf17aeb2cd3a2723de494c1dd558d1ab5b03c7657762c80923fcd37682c4' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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